Concentric multi-tube accumulator



Aug.V 19. 1969 KAzuc` s'uGlMuRA ETAL CONCENTRIC MULTI-TUBE ACCUMULATOR Filed aan. 24. 1967 -MAHQW' Kazaa Eugzmura Nabuyukz Sugzmura United States Patent ffice 3,461,914 Patented Aug. 19., 1969 3,461,914 CONCENTRIC MULTI-TUBE ACCUMULATOR Kazuo Sugimura and Nobuyuki Sugimura, both of 1416 Sodeshi-cho, Shizuoka-ken, Shimizu-shi, Japan Filed Jan. 24, 1967, Se'r. No. 611,410 Claims priority, application Japan, Feb. 3, 1966,

6,334 Int. Cl. F161 55/04, 55/02 U.S. Cl. 13S-30 2 Claims ABSTRACT F THE DISCLOSURE This accumulator consists of a number of tubes of elastic and flexible material, with different diameters, and of a pair of discs, which are integrally connected with each other by a `numbers of stays. These tubes are concentrically installed between the discs, to which both ends of tubes are air tightly lixed.

The chamber enclosed by the, innermost tube andk by the discs serves as a liquid tank; This chamber is connected with a liquid system through a port equipped in the disc.

The enclosed annular chambers between concentric tubes serve as a gas reservoir.

This invention relates to a kind of bladder type pressure liquid accumulator suitable for lower hydraulic pressures. With the conventional bladder type accumulator, consisting of a gas bag of elasticand flexible material installed in a liquid tank of rigid material and connected to a pressure liquid system, the bladder or the gas bag dellates or inates according to the pressure changefof liquid, to accumulate or discharge liquid from or to the system and at the same time absorb pressure pulsations and hydraulic shocks. This type is suitable for high pressure, but not for low liquid pressure, such as in water service or in pipe lines in the industries.

This invention is intended to eliminate the defects of conventional accumulators and toprovide an accumulator of simple construction suitable toserve in a hydraulic' system of low pressure, at a low cost i In the drawings, FIG. 1 is the longitudinal section of an embodiment of this invention, while FIG. 2 is that of another embodiment, FIG. 3 is their cross section, and FIG. 4 shows the state of the invented accumulator working under a certain hydraulic pressure'.

The accumulator of this invention comprises a cage-like shell 1 of a rigid material, either of metal or other suitable pressure resisting material, consisting of a pair of circular discs 2 and 3 which are integrally or rigidly connected together by a number of stays or bolts 4. A number of tubes 6, 7, 8 and 9 with different diameters, of elastic and exible material, are concentrically installed between the discs 2 and 3, the ends of each tube being air tightly fixed to the discs 2 and 3.

A chamber 11, defined by the innermost tube 6 and the two discs 2 and 3, serves as a pressure liquid tank, which is communicated with a pressure liquid system through a liquid port in the disc 2 or through a liquid inlet port 5 and an outlet port 5' provided in the discs 2 and 3 respectively. Each of the annular chambers 12, 13 and 14 dened by the concentric tubes 6, 7, 8, 9 and the two discs 2 and 3 serves as a pressure gas reservoir, in the same manner as in a conventional bladder type accumulator. These reservoirs, charged with gas under a certain standard .pressure (commonly charged with air under atmospheric pressure) jointly inflate or deate in response to any pressure change in the pressure liquid system, and cooperatively serve as a gas bag like that in a conventional bladder type accumulator.

When an accumulator, as shown in the FIG. 1 and FIG. 3 and as above described, is connected to a pressure liquid system through the liquid port-5 or through the ports 5 and 5', the gas reservoir inllates and deates so that the expanding force due to fluid' pressure acting on the cylindrical wall of the liquid resrvoir is balanced by the resultant of reacting forces against the same wall due to the elasticity of tubes 6, 7, -8 and 9`and the compressing force' due to gas pressure 5 in gas chambers 12, 13 and 14. FIG. 4 shows this balanced condition.

In FIG. 4, which shows the accumulator of FIG. 1 under liquid pressure, the cylindrical'wall 6 of the liquid reservoir deforms to 6' and the liquidv reservoir 11 expands to 11'. At the same time, the tubes 7, 8 and 9 expand respectively to 7', 48 and 9', and the chambers 12, 13 and 14 are compressed and deformed respectively to 12',l 13' and 14.

Now let gas pressure in chambers 12', 13' and 14' be respectively p2, p3 and p4, and let the surface area of tubes 6', 7, 8' and 9 be respectively s1, s2, s3 and s4. Then the expanding forces acting on'ffthe inner surfaces of'tubes 6', 7', 8 and 9' are respectively F1, F2, F3 and F4, which may be expressed as follows:

And let pa be the atmospheric pressure, then, compressive forces F4', F3', F2' and F1', exerted respectively by pressure pa, p4, p3 and p2, against the'external surfaces of tubes 9', 8', 7' and 6', may be expressed as follows:

F4'=Pas4, F3=P4S3, F2'=P3S2`,::F1' =P2S1 Let the reactional forces, due to th'e elasticity, which resist deformation of deformed tubes 6', 7, 8' and 9 be f S1, S2, S3 and S4 respectively. g

Then, in order that the liquid pressure in the liquid reservoir 11' and the atmospheric pressure surrounding gas reservoir 9 may balance with each other, the following equations must simultaneously be 'satisfied in relation to the above three groups of forces Fs, F"s and Ss.

This equation shows that the liquid pressure p1 is larger than the atmospheric pressure pa by S4 S3 S2 S1 S4 83 S2 S1 i.e., by selecting proper elasticity, thickness and surface area for each of elastic tubes 6, 7, 8 and 9, and further as occasion demands, by properly selecting the number of elastic tubes, an accumulator is obtained that is suitable for a pressure liquid system of any liquid pressure. Also, it is clear, by the above equations, that by increasing the number of elastic tubes, the accumulator is capable to accumulate fairly high pressure liquid.

Another superior characteristic of the accumulator of this invention is that the area of total surface of the-elastic tubes absorbs any shock which is induced in the pressure liquid system, so that the accumulator absorbs not only large hydraulic shocks but also smaller pressure pulsations, caused in comparatively low pressure liquid, which have so far been difficult to absorb. These benefits have actually been proved in a town Water service.

An accumulator, as embodied in FIG. 2, is to be installed, as already described, in a pressure liquid pipe line so that liquids are sent through the accumulator, which absorbs harmful pressure pulsations, which have been an inevitable source of trouble both in the oil industries and in water service.

Another merit of the invented accumulator is its low cost and easy operation, due to its simple construction.

We claim:

1. An accumulator comprising:

(A) a rigid cage-like shell comprising (1) a pair of end members and (2) a plurality of circumferentially spaced connecting members holding said end members in generally coaxial spaced apart relationship,

(3) one of said end members having a substantially concentric opening therethrough;

(B) a plurality of concentrically arranged elastic tube members, each having its opposite ends sealingly connected with the end members so that the tubular member spans the space between the end members,

(l) the innermost one of said elastic tube members providing a liquid chamber that is communicable through said opening with a hydraulic system,

(2) the outermost one of said tube members being spaced radially inwardly from the connecting members and having its exterior surface exposed to the atmosphere through the spaces between connecting members, and

(3) said tube members cooperating with one another to define substantially concentric annular chambers which are filled with gas and which surround the liquid chamber.

2. An accumulator comprising:

(A) a plurality of elastic tube members of different diameters disposed substantially concentrically; and

(B) a rigid cage-like shell cooperating with said tube members to dene an inner liquid chamber Surrounded by annular gas chambers, said shell comprising (l) a pair of end members, each sealingly connected with an end of all of said tubular members, and one of said end members having an opening therethrough by which the liquid chamber is communicable with a hydraulic system, and

(2) a plurality of circumferentially spaced connecting members securing said end members against relative motion, said connecting members -being radially spaced outwardly from the outermost tube member and the spaces between connecting members permitting the outer surface of the outer tube member to be exposed to the atmosphere.

References Cited UNITED STATES PATENTS HERBERT F. ROSS, Primary Examiner 

